Chapter-Chapter 10. Life Processes in Plants Science Curiosity class 7 in english Medium CBSE Notes

Chapter 10: Life Processes in Plants

Introduction: Plants are living organisms and they also perform various life processes to survive. Unlike animals, plants can prepare their own food. They carry out processes like nutrition, respiration, transportation, and excretion in their own unique way.

Plants play a very important role in maintaining balance in nature by producing food and oxygen.

This chapter covers the following topics:

• Life processes in plants
• Photosynthesis and nutrition
• Respiration in plants
• Transportation in plants
• Excretion in plants
• Role of plants in environment

Nutrition in Plants: Plants prepare their own food by a process called photosynthesis. They are known as autotrophs.

In this process, plants use sunlight, water, and carbon dioxide to make food in the form of glucose.

Example: Green plants use sunlight to prepare their food in leaves.

Photosynthesis: Photosynthesis is the process by which green plants prepare food using sunlight, chlorophyll, water, and carbon dioxide.

This process mainly takes place in the leaves.

Requirements for Photosynthesis:

• Sunlight
• Chlorophyll
• Water
• Carbon dioxide

Key Point: Plants are producers because they make their own food through photosynthesis.

Respiration in Plants: Like animals, plants also respire to release energy from food. In this process, oxygen is used and carbon dioxide is released.

Respiration occurs continuously in plants, both during day and night.

Types of Respiration:

• Aerobic Respiration: Takes place in presence of oxygen and releases more energy.
• Anaerobic Respiration: Takes place in absence of oxygen and releases less energy.

Example: Germinating seeds respire actively to get energy for growth.

Gaseous Exchange in Plants: Plants exchange gases through small openings called stomata, present on the surface of leaves.

Through stomata, plants take in carbon dioxide and release oxygen during photosynthesis, and take in oxygen and release carbon dioxide during respiration.

Transportation in Plants: Plants have a system to transport water, minerals, and food to different parts of the plant.

Main Transport Tissues:

• Xylem: Transports water and minerals from roots to other parts of the plant.
• Phloem: Transports food prepared in leaves to all parts of the plant.

Example: Water absorbed by roots moves upward through xylem to reach leaves.

Transpiration: Transpiration is the process of loss of water vapour from the surface of leaves through stomata.

This process helps in cooling the plant and also in the upward movement of water.

Key Point: Xylem transports water, while phloem transports food in plants.

Excretion in Plants: Plants also produce waste materials during different life processes. However, unlike animals, plants do not have a special excretory system. They remove waste in different ways.

• Some waste is stored in leaves, bark, or fruits
• Some waste is removed through stomata
• Some waste is excreted in the form of gums and resins

Example: Leaves that fall from trees often contain waste materials.

Role of Plants in Environment: Plants play a very important role in maintaining balance in nature.

• They produce oxygen during photosynthesis
• They absorb carbon dioxide from the atmosphere
• They provide food to animals and humans
• They help in maintaining ecological balance

Without plants, life on Earth would not be possible.

Importance of Photosynthesis:

• Provides food for all living organisms
• Maintains oxygen level in atmosphere
• Helps in energy flow in ecosystem

Example: Animals depend on plants directly or indirectly for food.

Overall Understanding: Plants carry out all life processes like nutrition, respiration, transportation, and excretion in their own way. These processes are essential for their growth and survival and also support life on Earth.

Key Point: Plants are essential for life as they produce food and oxygen and maintain environmental balance.

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